The following discussion of the background of the invention is merely provided to aid the reader in understanding the invention and is not admitted to describe or constitute prior art to the present invention.
Whooping cough is a highly contagious disease of the respiratory system. Symptoms of whooping cough include episodes of violent cough followed by an inspiratory whoop and sometimes vomiting. In extreme cases these symptoms lead to hypoxia, permanent brain damage or even death. The majority of cases (80-98%) are caused by the small gram-negative bacteria Bordetella pertussis; however, a significant minority of cases (2-20%) are caused by Bordetella parapertussis. (Mattoo et al., Clin. Microbiol. Rev., 18: 326-382, 2005). Symptoms of whooping cough caused by B. parapertussis are typically milder than those caused by B. pertussis; however, a differential diagnosis is difficult based on clinical symptomology alone. Very rarely are pertussis-like symptoms caused by infection with B. bronchiseptica or B. holmesii. 
Diagnosing whooping cough in its early stages can be difficult because the signs and symptoms resemble those of other common respiratory illnesses, such as a cold, the flu, or bronchitis. Traditionally, bacterial cultures have been used to definitively diagnose whooping cough. Mucus is obtained from the nose and/or throat of the patient and sent to a medical lab for culturing. Although positive results are regarded as conclusive, Bordetella cultures typically require 5 to 7 days to obtain a diagnosis. Bordetella sp. bacterial cultures are also prone to false negative results because of the fastidious nature of the bacteria.
Antibody assays, including FLISA, are also used to diagnose Bordetella sp. by detecting characteristic bacterial antigens. Most commonly, detection of the pertussis toxin protein is used as an indicium of Bordetella infection. Although these antibody-based assays have good sensitivity and specificity, they typically require a sample of patient blood, instead of a non-invasively obtained mucus sample, and further require the infection to be in the early and/or convalescent stage. These assays are therefore prone to false negative results if the patient sample is not obtained at the proper time in the disease process.
Other methods for detecting Bordetella infection include direct fluorescent antibody (DFA) testing and various PCR-based methods. DFA testing has the advantage of being able to detect Bordetella using non-invasively obtained mucus samples, but suffers from a lack of sensitivity. PCR-based assays are becoming more widely used.